Vane pump housing

ABSTRACT

An annular sleeve is radially deformed within a cylindrical bore to provide a housing for a pump having vanes slidable through slots in an eccentric rotor, the radially opposed edges of the vanes slidably contacting the inner surface of the sleeve.

United States Patent [191 Takahashi et al.

[451 Apr. 15, 1975 VANE PUMP HOUSING [75] Inventors: Koichi Takahashi,Yokohama;

Nobuteru Hitomi, Yokosuka; Tokiyoshi Yanai, Yokosuka; Manabu Tsunematsu,Yokosuka, all of Japan [73] Assignee: Nissan Motor Company, Limited,

Yokohama, Japan [22] Filed: Sept. 24, 1973 [21] Appl. No.: 399,716

[30] Foreign Application Priority Data Sept. 28, 1972 Japan 4796642 [52]US. Cl. 29/156.4 WL; 29/156.4 R; 29/445; 418/159; 418/150 [51] Int. ClB23p 15/00 [58] Field of Seareh..... 29/1564 WL, 156.4 R, 445; 418/159,150

[56] References Cited UNITED STATES PATENTS 2,467,121 4/1949 Ferris29/1564 R 2,627,650 2/1953 Ferris 3,637,332 H1972 McAnally 418/159Primary Examiner-C. W Lanham Assistant ExaminerDan C. Crane Attorney,Agent, or Firm-Robert E. Burns; Emmanuel J. Lobato; Bruce L. Adams [57]ABSTRACT An annular sleeve is radially deformed within a cylindricalbore to provide a housing for a pump having vanes slidable through slotsin an eccentric rotor, the radially opposed edges of the vanes slidablycontacting the inner surface of the sleeve.

3 Claims, 6 Drawing Figures FZATENTEE APR 1 51975 sum 1 at 2 VANE PUMPHOUSING The invention relates to a housing comprising a resilient innersleeve for a pump having vanes slidable through slots in an eccentricrotor, the radially opposed edges of the vanes slidably contacting theinner surface of the sleeve.

This type of pump housing has a right cylindrical interior surfacecomprising a section of circular profile and a section of non-circularprofile, the two sections being smoothly connected to form a closedcurve. In the prior art, the interior surfaces of pump housings of thistype have been formed either by using expensive computer controlledmachine tools, or by approximating the internal profile with a series ofcircular arcs cut by an ordinary lathe or grinder and finish machiningthe housing interior to eliminate the cusps produced by the approximaterough machining. In the latter case, such finish machining is quiteexpensive, and if it is not preformed, the vanes of the pump will abradeat a rapid rate.

It is therefore an object of the invention to provide a housing for avane pump as described above which is inexpensive to manufacture, can beproduced using ordinary machine tools, and which has a smooth internalsurface which will cause minimum abrasion of pump vanes which slidablycontact therewith.

This and other objects of the invention will become more clear from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIGS. 1, 2 and 3 are schematic views which illustrate the geometricbasis of the invention;

FIG. 4 is a longitudinal view, partly in section, of a pumpincorporating therein an embodiment of a pump housing according to theinvention;

FIG. 5 is a view taken on a line A-A of FIG. 4; and

FIG. 6 is a schematic view illustrating the assembly of a pump rotor andvane assembly into a pump housing embodying the invention.

Referring first to FIGS. 4 and 5, there is shown a pump casing (nonumeral) including a housing 10 of the invention, which defines thereina bore 12 and inlet and outlet passageways l4 and 16 which respectivelycommunicate with the bore 12 through inlet and outlet ports, althoughnot shown. A rotor 18 is rotatable within the bore 12 with a drive shaft20. Two vanes 22 and 24 are shown as being slidable through slots (nonumerals) in the rotor 18, radially opposed edges of which are inconstant sliding contact with the inner surface of a resilient annularsleeve 26 disposed in the bore 12. The annular sleeve 26 is radiallydeformed by means such as a wedge 28 as will be described below indetail. The resilience of the annular sleeve may be uniform ordis-uniform throughout its extent.

Referring now to FIG. 1, the geometric profile of the interior surfaceof the sleeve 26 is clearly shown, in which numerals 30, 32, 34 and 36desginate points on the profile. The rotor 18 is shown disposed withinthe sleeve 26 to rotate in the direction of an arrow 38. Only the vane22 is shown for simplicity.

The rotor 18 rotates about a point 0, which is the ori gin of arectangular coordinate system as shown. An arc -32-34 is that of acircle of radius R,,, which has a center 0' displaced by an offsetdistance 6 from the point 0 in a negative direction along the y axis.Edges 40 and 42 of the vane 22 slidably engage with the inner surface ofthe sleeve 26 as the rotor 18 rotates, the edge 40 being shown asengaging with the inner surface within the arc 30-32-34. As the rotor 18rotates and the edge 40 moves between the points 30 and 32, an arc 34-36is traced by the edge 42. As the edge 40 moves between the points 32 and34, the edge 42 traces an are 36-30. Thus, a closed curve is generatedin which the arc 30-32-34 is circular, and as is obvious to thoseskilled in the art, the arc 34-36-30 is noncircular. Thus, the interiorsurface of the sleeve 26 and thus the housing 10 comprises sections ofcircular and non-circular profile, and as mentioned above, has a rightcylindrical configuration.

In terms of a radius vector r, the arc 30-32-34 can be expressed as:

X -rcos9 and Y -rsin9, or

(Y-e) X R Combination of the above equations provides r 2ersin9 e R 0 orr esinG (R e cos 6)" (l) 0 0 1r Since the arc 34-36-30 is traced by theedge 42, it can be expressed as X (L-r) c059 and Y (L-r) sine (2) for O6 1r, where L is the length of the vane 22. It is understood that therelationship between the edges 40 and 42 is reversed as the edge 42enters the arc 30-32-34 and the edge 40 enters the arc 34-36-30.

Assuming for simplicity that the thickness of the sleeve 26 isinfinitesimal and that it is perfectly resilient, it is proposed by theinvention that if the sleeve 26 has an outer (or inner) circumferenceequal to the length of the arc 30-32-34-36-30, that the bore 12 iscylindrical and has a radius R and the wedge 28 (FIG. 5) radiallydeforms the sleeve 26 by a predetermined amount along the Y axis so thatits diameter along the Y axis is equal to L, and that the inner profileof the sleeve 26 and thus the housing 10 will closely approximate theconfiguration expressed by equations (1) and (2). It has been determinedexperimentally using sleeves of finite thickness that this phenomenonactually occurs.

In practice, the thickness of the sleeve 26 must be taken into account,which is facilitated by the fact that the inner and outer surfaces ofthe sleeve 26 are concentric. The inner circumference of the sleeve 26is selected to have a value equal to the arc length 30-32-3- 4-36-30,and the radius of the bore 12 is selected to be a value substantiallyequal to R plus the thickness (not designated) of the sleeve 26,although empirical corrections may be made if necessary for theresilient characteristics of the sleeve 26.

The arc length 30-32-34-36-30 is computed as follows:

An arc length I is l R (1r 2sin elR where I is the arc length 30-32-34,since it is a circular arc.

An arc length 1 is then computed from the following integral equation:

where I is the arc length 34-36-30. The inner circumference of thesleeve 26, designated as S is S 1 '2 where 8,, is the circumference30-32-34-36-30.

A radius R representing the inner radius of the sleeve 26, is then FIGS.2 and 3 illustrate the process of deforming the sleeve 26, assuming forsimplicity that it has an infinitesimal thickness. The rotor 18 is fixedin place on the shaft 20 within the bore 12, and the sleeve 26 isinserted loosely into the bore 12 with its bottom (as shown) contactingthe inner surface of the bore 12 at the point 32. The bore 12, sleeve26, and rotor 18 have radii R R and R respectively such that The wedge28 is then inserted into a recess (no numeral) in the housing such thatit applies a radial force P to the sleeve 26 in the Y direction. Thedimensions of the wedge 28 are selected such that the sleeve 26 will beradially deformed along the Y axis to an extent that its diameter alongthe Y axis will be substantially equal to L, and its chord along the Xaxis will assume the value L. The radius R of the rotor 18 is selectedso that the top (as shown) of the rotor 18 will be closely adjacent tothe inner surface of the sleeve 26 at the point 36 as the top of thesleeve 26 is deformed from its initial position 44 to the position 36.The final position of the sleeve 26 in relation to the bore 12 and therotor 18 is shown in FIG. 3.

FIG. 6 shows a preferred method of assembling the complete rotor andvane assembly into the housing 10. The vanes 22 and 24 are assembledinto the respective slots in the rotor 18, and the rotor 18 is fixed inplace on the shaft 20. The sleeve 26 is then placed in position in thebore and the rotor 18 and vanes 22 and 24 inserted in the sleeve. Inorder to minimize the stresses produced during deformation of the sleeve26, the vanes 22 and 24 are oriented at angles of 45 to the Y axis asshown. The wedge 28 is then inserted to deform the sleeve 26 to itsfinal position.

For reference, a practical example of the dimensions of anexperimentally successful pump housing produced in accordance with theinvention is listed below:

Diameter of bore l2 Approx 1.44 inch (36.64mm) Rotor l8 offset (e) 0.12inch (3mm) Sleeve 26 OD. L43 inch (36.38mm) Sleeve 26 ID. 1.35 inch(34.38mrn) Sleeve 26 displacement 0.01 inch (44-36) (0.38mm) Vane 22 or24 length L34 inch If desired the rotor 18 may be adapted for eccentricrotation within the sleeve 26 about a crank arm (not shown) having alength a and center at a point 46 as is clearly shown in FIG. 6.

Thus, a pump housing of the invention can be manufactured cheaply andeasily, and provides a highly finished interior surface of the requiredconfiguration for slidable engagement with pump vanes carried by arotor.

What is claimed is:

l. A method of manufacturing a housing for a vane pump, wherein vanesare slidably inserted through slots provided in a rotor, radiallyopposed vane edges protruding from the slots, the method comprising thesteps of:

forming in a casing a bore with a substantially circular profile;

inserting a loosely fitting annular resilient sleeve into said bore;

inserting the rotor and vane assembly into said resilient sleeve to berotatable relative to and within said resilient sleeve about a centerwhich is a predetermined distance from the center of the substantiallycircular profile, and

deforming a portion of said resilient sleeve radially inward by apredetermined amount in a direction of a line containing both centers,to form said housin'g,

wherein vane edges are caused to be in continuous slidable contact withthe interior surface of said resilient sleeve at all positions of therotatable rotor and vane assembly.

2. A method as claimed in claim I, wherein the step of deforming saidresilient sleeve results in said resilient sleeve to consist of asection of circular profile and a section of non-circular profile.

3. A method as claimed in claim 2, wherein the interior surface of saidsection of circular profile has an arc length of:

l, R,,(1r 2sin e/R and the interior surface of said section ofnon-circular profile has an arch length of:

l [(LI)2 (9 1 d9 wherein R radius of said bore L vane length r radiusvector e distance between the centers 0 angle formed between a vane andan X-axis.

Q Patent No. 3,877,127 Page 2 of 2 Fig.

1. A method of manufacturing a housing for a vane pump, wherein vanesare slidably inserted through slots provided in a rotor, radiallyopposed vane edges protruding from the slots, the method comprising thesteps of: forming in a casing a bore with a substantially circularprofile; inserting a loosely fitting annular resilient sleeve into saidbore; inserting the rotor and vane assembly into said resilient sleeveto be rotatable relative to and within said resilient sleeve about acenter which is a predetermined distance from the center of thesubstantially circular profile, and deforming a portion of saidresilient sleeve radially inward by a predetermined amount in adirection of a line containing both centers, to form said housing,wherein vane edges are caused to be in continuous slidable contact withthe interior surface of said resilient sleeve at all positions of therotatable rotor and vane assembly.
 2. A method as claimed in claim 1,wherein the step of deforming said resilient sleeve results in saidresilient sleeve to consist of a section of circular profile and asection of non-circular Profile.
 3. A method as claimed in claim 2,wherein the interior surface of said section of circular profile has anarc length of: l1 Ro( pi + 2sin 1e/Ro) and the interior surface of saidsection of non-circular profile has an arch length of: